Davis Cup
Version 3
Decagon Devices, Inc.
2365 NE Hopkins Court
Pullman, WA 99163
(509) 332-2756
© 2009-2010 Decagon Devices, Inc.
All rights reserved.
INTRODUCTION ........................................... 1
System And Hardware Compatibility ................ 1
How the Davis Cup Anemometer works
with the Em50 Logger................................. 1
COMPONENTS AND HARDWARE ................... 2
Hardware Kit:.................................................... 3
Tools and Materials Needed............................. 3
Attaching the Wind Cups .................................. 4
Testing the Anemometer .................................. 5
INSTALLING THE ANEMOMETER ................... 6
Choosing the Best Location.............................. 6
Mounting the Anemometer ............................... 6
MAINTENANCE ......................................... 11
TROUBLESHOOTING .................................. 12
CUSTOMER SUPPORT ............................... 14
SPECIFICATIONS ....................................... 15
The anemometer enables you to measure and display
wind-related conditions such as wind speed and wind
direction with your Em50 or Em50R logger.
System And Hardware Compatibility
Em50 Firmware version 1.19 or greater
ECH2O Utility 1.11 or greater
ECH2O Utility Mobile 1.18 or greater
How the Davis Cup Anemometer works
with the Em50 Logger
The Em50 measures the average wind direction in one
minute intervals. The value of the wind direction and
number of pulse counts (magnitude) are used to resolve
the wind direction into X and Y vector components. The
vector components from multiple one-minute readings
are summed together. The X and Y components are
combined to store the “dominant” or “weighted average”
wind direction for the measurement interval.
NOTE: When there is no wind, the vector math for
direction will resolve to zero (North) — regardless of the
actual direction of the wind vain.
The Em50 integrates wind speed pulses for one minute.
The highest one-minute count in each measurement
interval becomes the value for the gusts data. The
average of the one-minute counts becomes the average
speed for each measurement interval.
Components and Hardware
The anemometer includes the components listed below.
Please be sure you have all listed components before
continuing. The installation hardware kit contains the
items most commonly needed for the installation of the
anemometer. Which items you use from the kit depend
on where you install your unit. Assess your installation
and make sure you have all necessary parts, tools, and
materials before you begin.
Anemometer Arm with Cable
Anemometer Base
Wind Cups
Wind Vane
Drip Ring
Hardware Kit:
You may need to adapt or purchase additional hardware
to fit your individual requirements.
Two U-Bolts
Four ¼” Flat washers
Four ¼” Hex Nuts
Four ¼” x 3” Lag Screws
One #4-40 x 1 ¼” Pan Head Screw
One #4 Flat Washer
One #9 Lock Washer
One #4-40 Hex Nut
0.05” Allen Wrench
Note: If any of the hardware components are missing,
contact Decagon Devices about receiving replacement
hardware or other components.
Tools and Materials Needed
You will need the following tools and materials to install
your anemometer:
Cable Clips or Weather-Resistant Cable Ties
Make sure the clips or ties you use to secure the
anemometer cable have screw holes or other means
for mounting the cable. Do not use metal staples to
secure the cables.
Stainless Steel Hose Clamps
Small Screwdrivers
Adjustable Wrench
Hand-Held Compass or Local Area Map
Assembling the Anemometer
Attaching the Wind Cups
1. Before installing the anemometer, attach the wind
2. Push the wind cups onto the smaller of the two
stainless steel shafts .
3. Slide the wind cups as far up the shaft as possible.
4. Use the Allen wrench provided to tighten the set
screw on the side of the wind cups to approximately
finger tight.
5. Spin the wind cups. If they do not spin freely, loosen
the set screw, lower the cups slightly, then retighten
the set screw.
6. Repeat Step 4 until the wind cups spin freely.
Note: The wind vane installation is affected by the direction
of the mounting arm. Wind vane direction will be
modified during the anemometer installation.
Testing the Anemometer
Before beginning your installation, follow the
instructions below to test the anemometer wind speed
and wind direction functionality. You will need ECH2O
Utility or ECH2O Utility Mobile connected to an Em50
1. Connect anemometer cable to a port in a Em50
2. In the sensor pull-down menu for the chosen port in
ECH2O Utility, pick “Davis Cup Anemometer”
3. Enter your measurement interval.
4. Spin the wind cups.
5. Scan ports of the logger with ECH2O Utility. You
should see revolutions and direction.
6. Note the direction reading of the anemometer.
7. Grab the wind vane and twist about half a turn.
8. Scan ports, reading should have changed about 180
9. Disconnect the cables when you are finished testing
the anemometer.
Installing The Anemometer
Choosing the Best Location
Use the following guidelines to determine the best
location for your anemometer.
Install the anemometer in a location where wind
flow is unobstructed by trees and nearby
For the most accurate readings, the anemometer
should be mounted at least 4 feet (1.2 m) above
any obstructions.
You may do this by mounting the anemometer
on a television antenna mast, a wooden post, or a
metal pipe.
Mounting the Anemometer
Use the following procedures to mount the anemometer:
Checking the Base Orientation
You will need to know which way to orient the base
before installing it.
1. Insert the anemometer arm into the base
2. Push the #4-40 x 1 ¼” pan head screw through the
holes in the arm and the base as described in
“Attaching the Wind Vane” on page 9.
3. If the screw does not slide easily through the holes,
rotate the base 180° to line up the opposite holes,
then try again.
4. Note the correct base orientation for use when you
install the base later in the installation process.
Installing the Base on a
Wooden Post or Surface
1. Hold the anemometer base
against the wood surface and use a
pencil to mark the location of the
four holes on the base.
2. Use a drill with a 3/16” (5-mm)
drill bit to make pilot holes in
these locations.
Drive the lag screws through the holes in the
anemometer base and into the wood.
Installing on Antenna Mast or Metal Pipe
1. On an antenna mast or pipe with outside diameter of
7/8” to 1 1/4” (22 to 32 mm):
2. Hold the anemometer base
against the pipe and insert the
two U-bolts through the back of
the base so that the U-bolts
wrap around the pipe.
3. Place a 1/4” washer and a 1/420 hex nut over each end of the
U-bolts and use a wrench to
tighten the hex nuts.
Installing the Base on a Metal Mast or Pipe:
Outside Diameter Greater than 1¼ in. (32mm)
1. Use two stainless steel hose clamps to attach the
mounting base to masts or pipes larger than 1 1/4”
diameter, large enough to fit around the mast or pipe
and the anemometer base. You may purchase hose
clamps at your local hardware store.
2. Hold the anemometer base against the pipe and fasten the hose clamps over the anemometer base and
around the metal mast or pipe.
Attaching Arm to Base
1. Insert the anemometer arm into the anemometer
2. Guide the anemometer cable through the slot as you
insert the arm.
3. Insert the pan head screw into one of the holes in the
base and slide it through the arm.
4. Secure the pan head screw using the flat washer, lock
washer, and hex nut as shown.
Attaching the Wind Vane
To mount the wind vane, look at the ECH2O Utility
“scan” option display to orient the vane accurately.
1. Connect the anemometer cable to the Em50 or
Em50R and remove the wind vane attachment using
the included Allen wrench.
2. Press SCAN in ECH2O Utility or ECH2O Utility
Mobile to display wind direction in degrees.
3. Use a compass or map to determine true north.
4. Slowly turn the wind direction shaft with your
fingers. Stop turning when the weather station
display reaches 0 degrees.
5. Being careful to keep the stainless steel shaft from
turning, place the wind vane on the shaft with the
bullet-shaped nose of the vane pointing to true
6. Slide the wind vane down onto the shaft as far as it
will go.
7. Use the Allen wrench provided to tighten the set
screw on the side of the wind vane.
8. Test your assembly by pointing the wind vane in any
direction and (using the compass or map as a guide)
making sure the ECH2O Utility “Scan” displays the
correct wind direction. Readjust the vane if
9. Spin the wind cups to make sure you get a wind
speed reading. Readjust the cups if necessary.
10. Secure the cable to the metal mast or pipe with
electrical tape. Secure the rest of the cable according
to the directions below.
Securing the Cable
To prevent fraying or cutting the anemometer cable
where it is exposed to weather, it is very important to
secure it so it doesn’t whip about in the wind. Use cable
clips or weather resistant cable ties to secure the cable.
Place clips or ties approximately every 3 to 5 feet
(1 to 1.6 m).
Note: Do not use metal staples to secure cables. Metal staples
can cut the cables.
Your anemometer does not require any regular
DO NOT attempt to lubricate the wind cup shaft and
bearings or the wind vane shaft. Natural or synthetic
lubricants will inhibit the normal operation of the anemometer.
While your anemometer is designed to provide years of
trouble-free operation, occasionally problems may arise.
If you are having a problem with your unit, please check
the following troubleshooting procedures before sending
the unit in for repair. You will be able to solve many of
the problems yourself. If, after checking these procedures
you are unable to solve the problem, please call Decagon
Devices for further instructions (see next section on
“Customer Support”) Please do not return your unit for
repair without receiving prior authorization from
Decagon Devices.
Problem 1:
Wind speed reads 0 all the time or wind direction is
showing “ * * * ” in data field.
Make sure anemometer is plugged into port on
Em50 or Em50R.
Check for broken wire along length of
anemometer cable. Carefully check areas where
the cable has been secured.
Try dropping the wind cups approximately 1/16”
to 1/8” (1.5 to 3 mm) lower on the mounting
shaft. Use the included Allen wrench to loosen
and retighten the wind cup assembly.
If you still do not get a reading, the problem is
with the anemometer. Contact Decagon Devices
for return authorization.
Problem 2:
Wind speed reading seems too high or low.
Check installation by spinning wind cups. If the
wind cups spin freely and the weather station
displays a wind speed, the wind cups are installed
correctly. If the wind cups don’t spin freely, then
try dropping the wind cups approximately 1/16”
to 1/8” (1.5 to 3 mm).
Check for any obstructions blocking the wind
near the anemometer.
Problem 3:
The wind direction data always reports 0 (North)
whenever the wind speed is zero, even if the wind vain is
pointing a different direction.
The Em50 uses wind speed and direction to
calculate the dominant wind direction (see page
one: How the Davis Cup Anemometer works
with the Em50 Logger). Because this calculation
uses vector math, reported wind direction is zero
when there is no wind speed.
Customer Support
If you ever need assistance with your Anemometer, or if
you just have questions or feedback, there are several
ways to contact us.
Note: If you purchased your Anemometer through a
distributor, please contact them for assistance.
(800) 755-2751 – USA and Canada Only
(800) 332-2756 – International
Our Customer Support and Sales Representatives are
available Monday thru Friday, 8:00am–5:00pm Pacific
(509) 332-5158
Note: With any correspondence, please include your name,
contact information, instrument serial number(s), and a
description of your problem or question.
Wind Direction
1° increments
Accuracy: ± 7°
Wind Speed
Range: 2 to 129 mph, 4 to 209 kph, 1 to 58 m/s,
Accuracy: ± 5%
This product complies with the essential protection
requirements of the EC EMC Directive 89/336/EC.
This anemometer has been adapted to work with
Decagon Devices ECH2O System and is based on the
Standard Anemometer manufactured by Davis
Instruments. The technical information provided herein
is provided courtesy of
Decagon Devices, Inc.
2365 NE Hopkins Court
Pullman, WA 99163
(509) 332-2756
© 2009-2010 Decagon Devices, Inc.
All rights reserved.